1. Technical Field
This invention relates generally to seal assemblies, and more particularly to rotary shaft seal assemblies and their method of construction.
2. Related Art
Shaft seals are commonly used throughout numerous types of vehicle applications. Aside from the shaft seal establishing a reliable seal against a rotating shaft, both to prevent the ingress of contamination and the egress of desirable lubrication, it is desirable that the seal provide a minimal running torque against the shaft. A reduced running torque of the seal helps to enhance the overall fuel economy of the vehicle, as lower torque requires less parasitic horse power to turn the shaft, such as a crankshaft, for example, due to less drag produced by the shaft seal against the running surface of the shaft. It is also desirable that the seal be relatively easy to install over an end of the shaft upon which it rides and onto the shaft with minimal push-on force. Further, it is desirable that the seal be installed onto the shaft without having the seal lip becoming damaged and/or inverted. Of course, if made too easy, a tradeoff may be made with the ability of the seal lip to maintain a reliable seal against the running surface of the shaft. Accordingly, continual efforts are made to attain the desired aspects of seal assembly, while at the same time avoiding negatively impacting the ability of the seal to maintain a reliable seal against the running surface of the shaft in use.